Knurled closure

ABSTRACT

A method of forming an annular knurled band on two surfaces of a container closure by providing a generally cylindrical closure shell having a top panel and a depending annular skirt. Forming a plurality of outwardly directed knurled portions within a plurality of first circumferential arcs by outwardly reforming the arcs to establish in each knurled section a lower portion extending radially outwardly from the annular skirt and an upper portion formed as a continuous extension of the lower portion, extending upwardly and outwardly from the top panel. Forming a plurality of inwardly directed knurl portions in second circumferential arcs in alternating position with the outwardly directed knurl portions by restraining the second arcs against outward movement. The closure having both the outwardly directed and the inwardly directed knurled portions each of substantially uniform transverse width throughout their longitudinal extent. The knurling originates within the upper half of the skirt and terminates at its uppermost level in the upper panel.

United States Patent 1,495,722 5/1924 Anderson 1,810,706 6/1931 Hardiman-A ABSTRACT: A method of forming an annular knurled band on two surfaces ofa container closure by providing a generally cylindrical closure shell having a top panel and a depending annular skirt. Forming a plurality of outwardly directed knurled portions within a plurality of first circumferential arcs by outwardly reforming the arcs to establish in each knurled section a lower portion extending radially outwardly from the annular skirt and an upper portion formed as a continuous extension of the lower portion, extending upwardly and outwardly from the top panel. Forming a plurality of inwardly directed knurl portions in second circumferential arcs in alternating position with the outwardly directed knurl portions by restraining the second arcs against outward movement. The closure having both the outwardly directed and the inwardly directed knurled portions each of substantially uniform transverse width throughout their longitudinal extent. The knurling originates within the upper half of the skirt and tenninates at its uppermost level in the upper panel.

PATENTEmuv 30 I97: 3, 623 ,442

sum 1 UF 2 IN VE/V TOR. W/LBURN C0) WILL/5' mu MM A f forney KNURLED CLOSURE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to knurled closures and more specifically to torque-removable closure knurling having portions of outstruck enlarged diameter with respect to the closure shell diameter and a continuous annular knurled band formed partially within the closure skirt and partially within the closure top panel.

2. Prior Art It is known in the closure art to form various types of structural irregularities which facilitate manual engagement for applying a closure removal torque. Such irregularities frequently take the form of knurling which is provided in the closure skirt at circumferentially spaced positions.

Knurling may be provided in various ways. In plastic closures, for example, it may be integrally molded. In metal closures it is conventionally provided by applying a radially inwardly directed force to reform the closure skirt inwardly at spaced intervals about the circumference of the closure. The relief provided in this fashion produces knurled portions having a maximum diameter equal to or slightly less than the diameter of the original closure shell. The diameter of the recessed portions is substantially less. As such knurling is limited in maximum diameter by the closure diameter, only use of a larger diameter closure shell could provide an enlarged knurl.

It has also been known in some instances to employ outwardly directed deformation of a closure skirt to provide an enlarged knurl diameter. This provides some advantages over the objectionable features of the inwardly directed knurl mentioned above,

In order to improve the effectiveness of the knurling, it is frequently extended over the entire skirt. As the knurling is generally employed in closures having screw threads or lugs, the objective of maximum knurl length conflicts with the objective of obtaining effective threads or lugs. The knurls are, however, frequently extended downwardly over the threads.

There is lacking an effective method for obtaining a maximum efficiency simple knurl structure in a torque-operated closure which avoids the above mentioned problems.

SUMMARY OF THE INVENTION This invention provides a method of forming a closure provided with an annular knurled band having the outwardly directed knurled portion extending radially outwardly beyond the diameter of the closure shell or workpiece over an upper portion of the closure skirt and a portion of the closure top, The knurled band consists of outwardly directed knurled portions disposed in alternate circumferential position around the closure skirt with respect to inwardly directed knurled portions. The outwardly directed portions are preferably of generally V-shaped transverse cross-sectional configuration, while the inwardly directed portions are of substantially straight or flat transverse cross-sectional configuration, While, as a practical matter, there will be a slight curve to the inwardly directed portion, this would be considered to be substantially flat" herein. Each outwardly directed portion is formed within a first circumferential arc. The outwardly directed portions are preferably formed within first circumferential arcs totaling about to percent of the total circumference of that portion of the closure shell within which the annular knurled band is formed. The knurled portions of this invention may originate in the upper half of the closure skirt and extend continuously upwardly and curvingly radially inwardly through the top of the skirt and into the top panel.

The method of this invention provides for formation of alternate individual outwardly and inwardly directed knurl portions. The first circumferential arc is formed radially outwardly while the adjacent second circumferential arcs are restrained against radial outward movement. In this fashion, first circumferential arcs are moved radially outwardly along the skirt portion and upwardly and outwardly along the closure top panel. For a given outwardly directed knurl portion this is accomplished substantially simultaneously. The same restraining action along the length produces substantially simultaneous formation of an individual inwardly directed knurl portion over its entire length.

The total number of outwardly and inwardly directed knurl portions combine to form the annular knurled band which may be formed either simultaneously or progressively.

The total circumferential area covered by the first arcs is less than that covered by the second arcs. Preferably the first arcs cover a total of about 10 to 20 percent of the total circumference of that portion of the closure shell which will be occupied by the annular knurled band.

The transverse width of the outwardly directed knurl portions is preferably uniform throughout their length as is the case with respect to the transverse width of the inwardly directed knurl portions. The height of the outwardly directed knurl elements preferred exceeds the inwardly directed elements by about 0.020 to 0.030 inch.

The closure top panel has an inner portion, which is preferably substantially flat, and an annular outer portion which curves downwardly and radially outwardly to meet the closure skirt. The lower origin of the knurled band originates on the closure skirt at a position within the upper half and preferably the upper quarter of the closure skirt. The band extends initially substantially vertically upwardly and then continues over at least a major portion of the annular outer portion of the top panel. The origin of the knurled band is above any thread or lug elements, and terminates in the top panel at the uppermost portion of the band.

The outwardly directed knurl sections are of substantially V-shaped transverse cross-sectional configuration and the inwardly directed knurl portions are preferably of substantially flat transverse cross-sectional configuration.

The annular knurled band also serves to rigidify and protect the impact-susceptible upper corner of the closure.

It is an object of this invention to provide a knurled closure having an improved enlarged knurled structure which may be more readily manually engaged for closure application or removal, and a method of manufacturing the same.

It is another object of this invention to provide a knurled torque-removable closure which may be more effectively engaged by sealing machinery for securing a threaded 0r lugtype closure to a container.

It is another objectof this invention to provide a closure having continuous knurl portions of uniform transverse width throughout their length.

It is yet another object of this invention to provide a method of manufacturing a unitary metal closure providing an outwardly formed knurled band which provides protective rigidity to the closure in the region where the top panel connects with the depending skirt.

Other objects and advantages of this invention will be understood from the following description of the invention on reference to the drawings appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a closure incorporating an embodiment of this invention.

FIG. 2 is an elevational view, partially in section, of a closure of this invention.

FIG. 3 is a plan view partially in section of a closure of this invention.

FIG. 4 is a detailed fragmentary sectional view of a portion ofthe closure shell out of which the closure will be formed.

FIG. 5 shows an intermediate stage of the method of the invention with the outwardly directed knurls being partially formed.

FIG. 6 shows another stage of the method of this invention with one knurl completely formed.

F IG. 7 is a fragmentary sectional elevation showing the tooling in engagement with both the closure skirt and the top panel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now more specifically to the drawings, FIG. 1 shows a threaded closure 2 which has a skirt 4 depending from a panel 6. An annular knurled band 8, in the form illustrated, has the knurled elements originating in the upper portion of the closure skirt 4 and extending continuously upwardly through the top of the skirt and into the closure panel 6. As is shown in FIGS. 2 and 3, the knurled band 8 has outwardly directed knurled portions I4 which are uniformly positioned around the circumference of the closure in alternate positions with respect to the inwardly directed portions 16.

As is shown in FIGS. 2 and 3, the outwardly directed knurled portions 14 establish a diameter D which is greater than diameter D, which was the original diameter of the closure shell skirt. The inwardly directed knurled portions 16 have a diameter D, substantially equal to the original shell skirt diameter. The knurled structure, therefore, provides a minimum diameter D, approximating that of the original shell and an enlarged diameter D exceeding that of th 'original shell. FIG. 7, which is a fragmentary elevation of the closirre positioned in the forming dies, shows an inwardly directed knurl portion in the solid lines and an outwardly directed knurl portion in the dotted lines. The top panel 6 has an annular outer portion (defined by the letter T) which surrounds the substantially flat inner top panel portion. The annular outer portion T has a curved downwardly and radially outwardly configuration and terminates at its lower end by merging into the closure skirt 4.

As is shown in FIGS. 1 through 3 and 7, the annular band defined by knurl portions l4, 16, therefore, has a lower origin within the upper one-half of the closure skirt and extends continuously upwardly through at least a major portion of the annular outer portion of top panel 6. The terminus of the band is disposed at the uppermost portion thereof, within the top panel 6. From the origin the band extends initially vertically upwardly within the skirt 4 and then curves upwardly and radially inwardly within the annular outer portion T of the top panel 6. While the band may continue into the inner top panel portion, it is preferred that the terminus be positioned in relatively close proximity to the radially innermost end of the annular outer portion T.

In this fashion, the two-surface coverage by the knurled portions l4, 16, which cover a relatively small portion of the closure, provides an outwardly enlarged continuous closure knurl of definite extent which facilitates machine engagement for applying the closure to a container as well as manual engagement for removal thereof. In addition, it provides an annular reinforced region at the area of joining of the top panel 6 and skirt 4 to provide increased resistance to the closure 2.

The term torque-removable closure" as used herein shall refer to a closure having continuous or discontinuous threads, lugs or other container finish engaging protrusions which require the application of torque to apply or remove the closure from a container. It is not important whether the container finish engaging protrusions are formed before knurling, simultaneously therewith or thereafter.

In FIG. 4 a section of a generally cylindrical closure shell skirt is shown; the dotted lines reflecting the outwardly curved knurl elements 14 to be formed and the intermediate inwardly directed knurl elements 16 shown in solid lines. A series of first circumferential arcs A, are of substantially the same size and disposed in circumferential alternating position with respect to a series of second circumferential arcs A, which are also all of substantially the same size. These arcs A,, A while for convenience of illustration are shown in the skirt, will be understood to extend upwardly therefrom into the top panel 6 to the terminus of the annular knurled band. Circumferential are A, provides the metal to be used in forming element 14 of height h. Arc A which is longer than are A,, provides the metal for forming element 16.

By means of the method of this invention, the outwardly directed knurl elements 14 are formed by outwardly reforming are A, to a height h. This generally involves stretching or thinning of the metal in are A,. It will be appreciated that when each knurl portion 14 is created from an are A,, the entire portion 14 may be formed substantially simultaneously by reforming the entire arc A, from the lower origin within the skirt 4 to the upper terminus within the top panel 6. The lower sector of the knurl portion 14 is within the skirt 4 and is disposed substantially vertically while the upstanding upper portion which is formed as a continuous extension of the lower portion extends upwardly and radially inwardly into the top panel while being raised with respect thereto. The annular knurled band preferably has its origin within the upper quarter of the closure skirt at a position above the thread elements on the closure.

The inwardly directed knurl portions 16 are formed by substantially completely resisting movement of are A, during formation of portions 14. In this fashion portions 16 have a diameter D, substantially equal to the original shell diameter and portions 14 have a diameter D, equivalent to double the height h of portions 14.

By means of the method of this invention, the larger element 16 is formed without substantial movement of the metal in arc A Smaller are A, is merely formed radially outwardly to festablish element 14. Thus, instead of overcoming the substantial resistance required to reform large arc A inwardly, to

establish knurled band 8, smaller are A, is merely reformed radially outwardly. The difference in length of arcs A,, A is significant as it is easier to reform the smaller are A, radially outwardly to form smaller element 14, than to reform larger are A, radially inwardly to form element I6. By proper selection of the lengths of A,, A, the total number of elements I4, 16 can be determined, as well as the height h of the element, for any closure of given diameter. The height I: of element 14, of course, determines the increase in diameter D, over D This may be slightly varied by permitting some movement of A during the forming stages, but this is not essential.

One significant feature of this invention is the permitted variations in the diameter D of the outwardly directed knurled elements 14 with respect to height h and circumferential frequency and width of elements 14, 16. While the beneficial results of this invention can be obtained with are A, larger than are A,, the preferred arrangement provides a total circumferential extent of arcs A, equal to about 10 to 20 percent of the total circumference of the closure shell. The total circumferential extent of all of arcs A then equals about 80 to '90 percent of the shell circumference. This results in outwardly directed knurled sections 14 being of a readily formable size, and provides a desired section height h, coupled with sufficient circumferential gap between adjacent sections 14 to facilitate gripping. The preferred exterior height Jr of hollow sections 14 with respect to sections 16 is about 0.020 to 0.030 inch, which results in diameter D, exceeding diameter D, by a maximum of about 0.040 to 0.060 inch. The height h may vary alopg the length of the knurl portion 14, but will reach a maximum intermediate opposed ends thereof.

The formation of annular knurled band 8 may be effected in the manner shown in FIGS. 5 through 7. Inner die member 20 has bosses 22 which are adapted to cooperate with recesses 26 of outer die 24. In FIG. 5, forming has been initiated, while in FIG. 6 the elements l4, 16 have been formed. In FIG. 5, center boss 22 of inner die 20 has initiated deformation of the one outwardly directed knurl portion. It is noted that portions of die 24 abut the adjacent arcs A in surface-to-surface contact which resists outward movement thereof. In FIG. 6, the formation of the center knurl portion 14 is substantially complete while the adjacent ones are in the initial forming stages.

FIG. 7 illustrates a die configuration for simultaneously forming the full longitudinal extent of an individual portion 14 or 16 over the full extent from skirt origin to top panel terminus. The terminus may be within the annular outer portion of top panel 6 or within the inner top panel portion in close proximity to portion T. Little if any added benefit is obtained by extending the terminus at a position toward the center of top panel 6. Outer die 24 is provided with an extension 28 which incorporates a curved transition and a top panel contacting surface. lnner die 24 is provided with a panel-supporting surface 30. Extension 28 and surface 30 have complementary portions which are continuations of bosses 22 and recesses 26.

It will be appreciated that as a result of this method of forming knurling by moving metal outwardly with respect to the original closure shell, the top extension 28 serves as an added restraint which contributes to effective formation of continuous knurling on the skirt and top panel. The outer die 24 therefore provides restraining surfaces engaging the skirt to resist radial expansion where elements 16 are to be formed and also to resist, through extension 28, upward deformation of the upper sector of elements 16.

In the form illustrated, while the individual portion 14, such as the center one in FIGS. 5 and 6, is substantially simultaneously formed, the adjacent arcs A are in a different stage of formation. The formation of the annular knurled band is therefore being effected progressively around the circumference of the closure. This process may conveniently also be effected simultaneously by means of continuous dies or progressively as by roller-type dies. In general, it should be noted that increased speed of production would be obtained by simultaneous formation. Progressive formation of rollertype dies may be accomplished at an increased speed by employing dies of sufficient size to have several outwardly directed elements 14 in a forming stage simultaneously. Also, the use of progressive roller-type dies provides the distinct advantage of being able to combine the knurling operation with a progressive roller-type threaded or lug formation, thereby eliminating the need for a separate knurling station.

With respect to configuration, the outwardly directed knurled sections 14 may have a suitable transverse cross-sectional configuration which is generally V-shaped The inwardly directed knurled sections 16 preferably have a straight or flat transverse cross-sectional configuration. (As a practical matter, the sections 16 will generally be an arc A which has a radius approximating that of the closure skirt, but this, for purposes of the present description, will be considered as being generally flat or straight") One problem frequently encountered in the hoppering and handling of closures prior to afiixation is undesired nesting or interlocking created by the top of one closure entering into the opening in the bottom of another. This frequently impedes proper feeding of closures and requires a brief cessation of production. The outwardly projected knurled band of this invention provides an enlarged closure top which resists such nesting and interlock.

The closure is preferably made from a unitary deformable substantially rigid shell which may conveniently be of metal, such as aluminum or tin plate.

While it forms no part of this invention and has for purposes of clarity of illustration not been shown, it is of course contemplated that the closure may be provided with a suitable sealing gasket such as a disc, ring, inner shell or other convenient form.

It will be appreciated that the annular knurled band provides a rigidified corner structure which will increase the impact resistance of the closure in this damage-susceptible area.

It will be appreciated that as a result of diameter D being greater than diameter D the torque arms are larger, thereby providing a finite increase in mechanical advantage for one turning the closure end to remove it or to secure it on the container. The benefit is obtained simply and without the need to employ additional material in the closure shell.

It will, therefore, be appreciated that the method and closure of this invention provide an economical means for effecting an improved knurled closure structure. Without requiring additional metal in the closure shell or workpiece, the closure skirt may be provided with an upstanding annular knurl band of increased diameter. This knurl may have a predetermined height h made from predetermined arc widths (A A The knurling may originate in the upper half, preferably the upper quarter, of the skirt portion and extend continuously upwardly through the closure panel. The added height of the knurls and presence in both skirt and top panel result in a knurled band having a greater difference in height between the sections l4, l6 and an enlarged diameter D This facilitates more effective engagement by hand or machine to apply torque to the closure in effecting application or removal. Also, the increased diameter provides an increased mechanical efficiency due to the added torque arm length. All of this is accomplished simply, while providing a distinctive closure of improved appearance and functioning.

While for purposes of clarity of expression and full disclosure, certain specific forms of the invention have been expressly referred to, it would be appreciated that numerous variations may be made without departing from the scope of the invention.

lclaim:

l. A method of forming a knurled container closure comprising providing a generally cylindrical closure shell having a top panel and a depending annular skirt,

forming a plurality of continuous outwardly directed knurled portions each within one of a plurality of first circumferential arcs all of substantially the same size by outwardly reforming said first arcs to establish in each said knurled portion a lower sector extending radially outwardly from said annular skirt to a diameter greater than the original diameter of said skirt and up upper sector formed continuously with said lower sector extending upwardly and radially inwardly into said top panel,

forming a plurality of continuous inwardly directed knurled portions each within one of a plurality of second circumferential arcs all of substantially the same size and disposed in circumferentially alternating positions with respect to said first arcs by restraining said second arcs against substantial outward deformation during formation of said outwardly directed knurled portions,

forming the lower extremities of said outwardly and inwardly directed knurled portions within the upper onehalf of said depending annular skirt, and

forming the upper extremities of said outwardly and inwardly directed knurled portions within said top panel spaced radially outwardly from the center of said top panel.

2. The method of claim 1 including forming said outwardly directed knurled portions by outward thinning deformation of said first arcs,

said first circumferential arcs occupying about 10 to 20 percent of the total circumference of said closure shell,

said second circumferential arcs occupying about to percent of the total circumference of said closure shell, and

forming a torque-removable closure by establishing inwardly directed container-engaging means within said closure skirt below said outwardly and inwardly directed knurled portions.

3. The method of claim 2 including forming said outwardly and inwardly directed knurled portions sequentially around the circumference of said shell, forming all parts of each individual said knurled portion substantially simultaneously,

forming each said outwardly directed knurled portion with a substantially uniform transverse width throughout its continuous length, and

forming each said inwardly directed knurled portion with a substantially uniform transverse width throughout its continuous length.

4. The method ofclaim 2 including forming said outwardly directed knurled portions with a varying height with a maximum height of about 0.020 to 0.030 inch being effected intermediate the ends of said outwardly directed knurled portion.

5. The method of claim 4 including forming each said outwardly and inwardly disposed knurled portion with an origin disposed within the upper onequarter of said closure shell, and

forming each said outwardly and inwardly disposed knurled portion with a vertically upwardly directed portion adjacent its origin and having an upwardly and radially inwardly directed curved portion connecting therewith terminating at the uppermost level of said knurled portions.

* I F t UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,623,442 Dated November 30, 1971 Inventor(s) Wilburn C. Willis It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 3, line 55, after "resistance" change "to" to --for--.

Col. line 24, after "to" insert --D P Col. 4, line 3%, after "diameter" delete "D over D and insert "D over D Signed and sealed this 8th day of May 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attestinq Officer Commissioner of Patents IRM PO-1050l10-59I USCOMM-DC 60376-969 us, GOVERNMENT PRINTING OFFICE I was 0-366-334 

1. A method of foRming a knurled container closure comprising providing a generally cylindrical closure shell having a top panel and a depending annular skirt, forming a plurality of continuous outwardly directed knurled portions each within one of a plurality of first circumferential arcs all of substantially the same size by outwardly reforming said first arcs to establish in each said knurled portion a lower sector extending radially outwardly from said annular skirt to a diameter greater than the original diameter of said skirt and up upper sector formed continuously with said lower sector extending upwardly and radially inwardly into said top panel, forming a plurality of continuous inwardly directed knurled portions each within one of a plurality of second circumferential arcs all of substantially the same size and disposed in circumferentially alternating positions with respect to said first arcs by restraining said second arcs against substantial outward deformation during formation of said outwardly directed knurled portions, forming the lower extremities of said outwardly and inwardly directed knurled portions within the upper one-half of said depending annular skirt, and forming the upper extremities of said outwardly and inwardly directed knurled portions within said top panel spaced radially outwardly from the center of said top panel.
 2. The method of claim 1 including forming said outwardly directed knurled portions by outward thinning deformation of said first arcs, said first circumferential arcs occupying about 10 to 20 percent of the total circumference of said closure shell, said second circumferential arcs occupying about 80 to 90 percent of the total circumference of said closure shell, and forming a torque-removable closure by establishing inwardly directed container-engaging means within said closure skirt below said outwardly and inwardly directed knurled portions.
 3. The method of claim 2 including forming said outwardly and inwardly directed knurled portions sequentially around the circumference of said shell, forming all parts of each individual said knurled portion substantially simultaneously, forming each said outwardly directed knurled portion with a substantially uniform transverse width throughout its continuous length, and forming each said inwardly directed knurled portion with a substantially uniform transverse width throughout its continuous length.
 4. The method of claim 2 including forming said outwardly directed knurled portions with a varying height with a maximum height of about 0.020 to 0.030 inch being effected intermediate the ends of said outwardly directed knurled portion.
 5. The method of claim 4 including forming each said outwardly and inwardly disposed knurled portion with an origin disposed within the upper one-quarter of said closure shell, and forming each said outwardly and inwardly disposed knurled portion with a vertically upwardly directed portion adjacent its origin and having an upwardly and radially inwardly directed curved portion connecting therewith terminating at the uppermost level of said knurled portions.
 6. The method of claim 4 including forming each said first circumferential arc into one said outwardly directed knurled portion of generally V-shaped hollow transverse cross-sectional configuration, simultaneously restraining said second circumferential arcs disposed immediately adjacent said first circumferential arcs against outward movement to establish a substantially flat inwardly directed knurled portion, and forming said outwardly directed knurled portions with a transverse width less than that of said inwardly directed knurled portions. 